The present invention relates to an ink jet head which is a main part of an ink jet head recording apparatus ejecting ink drops to thereby attach the ink drops onto recording paper only when recording is required; a manufacturing method therefor; and the ink jet recording apparatus.
An ink jet recording apparatus has many advantages in that noise is extremely small at the time of recording, printing can be performed at a high speed, freedom of ink is high so that inexpensive cheap ordinary paper can be used, and so on. Of the apparatus, a so-called ink-on-demand system ejecting ink drops only when recording is required is becoming the mainstream currently because it is not necessary to recover ink drops unnecessary for recording.
One type of ink jet recording apparatus adopting this ink-on-demand system has an ink jet head in a system using electrostatic power (e.g. JP-A-6-71882) as a driving system for ejecting ink. This system has advantages in that it is small in size, high in density, high in printing quality and long in life. This ink jet head of the system using electrostatic power is manufactured by bonding an Si substrate finished by micro-machining technique, with a glass having electrodes, as disclosed in the above JP-A-6-71882. A plurality of chips of ink jet heads are formed in a lump on a single substrate, and separated from each other by dicing, so that the individual ink jet heads can be obtained.
However, as an ink jet recording apparatus has become to perform printing in colors, and printing at a high speed, it has become necessary that an ink jet head has a multi-nozzle structure. When this multi-nozzle structure is realized by arranging conventional one-nozzle-line head chips in parallel in a plane so as to form a plurality of nozzle lines, the size of head chips as a whole becomes large. That is, when an ink jet head having a plurality of nozzle lines is formed in a lump on a single substrate, the number of head chips extracted from the single substrate is reduced because the head chip size becomes large. Accordingly, the cost of an ink jet head is increased.
It is therefore an object of the present invention to provide an ink jet head in which a multi-nozzle structure is realized without increasing the size and without increasing the cost.
In addition to the above-mentioned object, it is another object of the invention to provide an ink jet head in which highly accurate alignment of ink jet head chips is realized when a multi-nozzle structure is realized.
An ink jet head according to the present invention is constituted by a stacked body in which a plurality of ink jet head chips are stacked one on another at predetermined intervals, each of the chips including a plurality of nozzle holes for ejecting ink drops, ejection chambers connected to the nozzle holes respectively, a diaphragm constituting at least one wall of each of the ejection chambers, and a driving means for producing transformation in the diaphragm. Further, the driving means is constituted by an electrode for transforming the diaphragm by electrostatic power, the diaphragm being formed on an Si substrate. Thus, the ink jet head is applied to a driving method of the electrostatic system.
According to the present invention, an ink jet head is thus configured by stacking ink jet head chips one on another, so that the ink jet head can have a multi-nozzle structure, and can cope with color printing and high-speed printing. In addition, since it will suffice if small ink jet head chips are merely stacked one on another, the number of ink jet head chips which can be obtained from one substrate is increased. Therefore, since it will suffice if normal ink jet head chips are selected and assembled, the yield is improved. In addition, since the area of the nozzle surface in which nozzle holes are arranged becomes small, the movement of an ink jet head at the time of printing can be reduced and the space efficiency inside the printer can be improved. Further, since ink jet head chips are stacked one on another at predetermined intervals, it is possible to avoid the influence of scattering in the outer size of the ink jet head chips and in the thickness of a bonding agent.
In the above ink jet head according to the present invention, a plurality of grooves for acting as guides upon stacking of the ink jet head chips are formed in an end surface on the nozzle hole side of or in each of opposite side surfaces of each of the ink jet head chips so that the alignment of the ink jet head chips is performed with these grooves as guides. Accordingly, it is possible to make alignment of ink jet chips easily and with high accuracy.
An ink jet head according to the present invention comprises a stacked body in which a plurality of ink jet head chips are stacked one on another at predetermined intervals, each of the ink jet head chips including a plurality of aperture portions for allowing ink drops to flow therethrough, ejection chambers connected to the aperture portions respectively, a diaphragm constituting at least one wall of each of the ejection chambers, and a driving means for producing transformation in the diaphragm, wherein a nozzle plate having a plurality of nozzle holes for ejecting the ink drops from the aperture portions is bonded with the stacked body. The driving means is constituted by an electrode for transforming the diaphragm by electrostatic power, and the diaphragm is formed on an Si substrate. Thus, the ink jet head is applied to a driving method of the electrostatic system.
According to the present invention, since a nozzle plate is adopted, the effect that the position accuracy of nozzle holes is improved is obtained in addition to the above-mentioned effects.
In the ink jet head using a nozzle plate according to the present invention, a plurality of guiding grooves are provided in an end surface on the aperture portion side of each of the ink jet head chips, and protrusion portions to be inserted into the grooves are provided in the nozzle plate. This nozzle plate functions as an alignment jig and the alignment of the ink jet head chips is made easier.
Further, in an ink jet head manufacturing method for manufacturing an ink jet head according to the present invention, in the case where a plurality of grooves are provided as guides for perform stacking in an end surface on the nozzle hole side of or in each of opposite side surfaces of each of the ink jet head chips, the plurality of grooves are produced by anisotropic etching, and alignment of the ink jet head chips is performed by inserting alignment members of an alignment jig into the plurality of grooves. Accordingly, the alignment of the ink jet head chips is made easier.
Further, in an ink jet head manufacturing method for manufacturing an ink jet head according to the present invention, in the case where a plurality of guiding grooves are provided in an end surface on the aperture portion side of each of the ink jet head chips and protrusion portions to be inserted into the grooves are provided in the nozzle plate, the grooves and the protrusion portions are produced by anisotropic etching, and alignment of the ink jet head chips is performed by inserting the protrusion portions into the plurality of grooves. The nozzle plate performs a role as an alignment jig to thereby make the alignment of ink jet head chips easier.
In addition, an ink jet recording apparatus according to the present invention is mounted with the above-mentioned ink jet head to thereby realize a recording apparatus which can cope with color printing and high-speed printing.